MPEG format is a widely used multimedia file format thanks to its convenience and compatibility. MPEG-4 format, the most recently suggested version of the MPEG file format, contains almost all types of multimedia data as its internal media block.
However, even MPEG-4 format contains the other MPEG-4 file as its internal media block, and so it does not enable convenient access to a detail media resource (elementary stream (ES)) contained in another MPEG-4 file.